// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/files/file_util.h"

#include <io.h>
#include <psapi.h>
#include <shellapi.h>
#include <shlobj.h>
#include <stddef.h>
#include <stdint.h>
#include <time.h>
#include <windows.h>
//#include <winsock2.h>

#include <algorithm>
#include <limits>
#include <string>

#include "base/files/file_enumerator.h"
#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/metrics/histogram.h"
#include "base/process/process_handle.h"
#include "base/rand_util.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "base/threading/thread_restrictions.h"
#include "base/time/time.h"
#include "base/win/scoped_handle.h"
#include "base/win/windows_version.h"

namespace base {

namespace {

    const DWORD kFileShareAll = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;

    // Deletes all files and directories in a path.
    // Returns false on the first failure it encounters.
    bool DeleteFileRecursive(const FilePath& path,
        const FilePath::StringType& pattern,
        bool recursive)
    {
        FileEnumerator traversal(path, false,
            FileEnumerator::FILES | FileEnumerator::DIRECTORIES,
            pattern);
        for (FilePath current = traversal.Next(); !current.empty();
             current = traversal.Next()) {
            // Try to clear the read-only bit if we find it.
            FileEnumerator::FileInfo info = traversal.GetInfo();
            if ((info.find_data().dwFileAttributes & FILE_ATTRIBUTE_READONLY) && (recursive || !info.IsDirectory())) {
                SetFileAttributes(
                    current.value().c_str(),
                    info.find_data().dwFileAttributes & ~FILE_ATTRIBUTE_READONLY);
            }

            if (info.IsDirectory()) {
                if (recursive && (!DeleteFileRecursive(current, pattern, true) || !RemoveDirectory(current.value().c_str())))
                    return false;
            } else if (!::DeleteFile(current.value().c_str())) {
                return false;
            }
        }
        return true;
    }

} // namespace

FilePath MakeAbsoluteFilePath(const FilePath& input)
{
    ThreadRestrictions::AssertIOAllowed();
    wchar_t file_path[MAX_PATH];
    if (!_wfullpath(file_path, input.value().c_str(), MAX_PATH))
        return FilePath();
    return FilePath(file_path);
}

bool DeleteFile(const FilePath& path, bool recursive)
{
    ThreadRestrictions::AssertIOAllowed();

    if (path.empty())
        return true;

    if (path.value().length() >= MAX_PATH)
        return false;

    // Handle any path with wildcards.
    if (path.BaseName().value().find_first_of(L"*?") != FilePath::StringType::npos) {
        return DeleteFileRecursive(path.DirName(), path.BaseName().value(),
            recursive);
    }
    DWORD attr = GetFileAttributes(path.value().c_str());
    // We're done if we can't find the path.
    if (attr == INVALID_FILE_ATTRIBUTES)
        return true;
    // We may need to clear the read-only bit.
    if ((attr & FILE_ATTRIBUTE_READONLY) && !SetFileAttributes(path.value().c_str(), attr & ~FILE_ATTRIBUTE_READONLY)) {
        return false;
    }
    // Directories are handled differently if they're recursive.
    if (!(attr & FILE_ATTRIBUTE_DIRECTORY))
        return !!::DeleteFile(path.value().c_str());
    // Handle a simple, single file delete.
    if (!recursive || DeleteFileRecursive(path, L"*", true))
        return !!RemoveDirectory(path.value().c_str());

    return false;
}

bool DeleteFileAfterReboot(const FilePath& path)
{
    ThreadRestrictions::AssertIOAllowed();

    if (path.value().length() >= MAX_PATH)
        return false;

    return MoveFileEx(path.value().c_str(), NULL,
               MOVEFILE_DELAY_UNTIL_REBOOT | MOVEFILE_REPLACE_EXISTING)
        != FALSE;
}

bool ReplaceFile(const FilePath& from_path,
    const FilePath& to_path,
    File::Error* error)
{
    ThreadRestrictions::AssertIOAllowed();
    // Try a simple move first.  It will only succeed when |to_path| doesn't
    // already exist.
    if (::MoveFile(from_path.value().c_str(), to_path.value().c_str()))
        return true;
    // Try the full-blown replace if the move fails, as ReplaceFile will only
    // succeed when |to_path| does exist. When writing to a network share, we may
    // not be able to change the ACLs. Ignore ACL errors then
    // (REPLACEFILE_IGNORE_MERGE_ERRORS).
    if (::ReplaceFile(to_path.value().c_str(), from_path.value().c_str(), NULL,
            REPLACEFILE_IGNORE_MERGE_ERRORS, NULL, NULL)) {
        return true;
    }
    if (error)
        *error = File::OSErrorToFileError(GetLastError());
    return false;
}

bool CopyDirectory(const FilePath& from_path, const FilePath& to_path,
    bool recursive)
{
    // NOTE(maruel): Previous version of this function used to call
    // SHFileOperation().  This used to copy the file attributes and extended
    // attributes, OLE structured storage, NTFS file system alternate data
    // streams, SECURITY_DESCRIPTOR. In practice, this is not what we want, we
    // want the containing directory to propagate its SECURITY_DESCRIPTOR.
    ThreadRestrictions::AssertIOAllowed();

    // NOTE: I suspect we could support longer paths, but that would involve
    // analyzing all our usage of files.
    if (from_path.value().length() >= MAX_PATH || to_path.value().length() >= MAX_PATH) {
        return false;
    }

    // This function does not properly handle destinations within the source.
    FilePath real_to_path = to_path;
    if (PathExists(real_to_path)) {
        real_to_path = MakeAbsoluteFilePath(real_to_path);
        if (real_to_path.empty())
            return false;
    } else {
        real_to_path = MakeAbsoluteFilePath(real_to_path.DirName());
        if (real_to_path.empty())
            return false;
    }
    FilePath real_from_path = MakeAbsoluteFilePath(from_path);
    if (real_from_path.empty())
        return false;
    if (real_to_path.value().size() >= real_from_path.value().size() && real_to_path.value().compare(0, real_from_path.value().size(), real_from_path.value()) == 0) {
        return false;
    }

    int traverse_type = FileEnumerator::FILES;
    if (recursive)
        traverse_type |= FileEnumerator::DIRECTORIES;
    FileEnumerator traversal(from_path, recursive, traverse_type);

    if (!PathExists(from_path)) {
        DLOG(ERROR) << "CopyDirectory() couldn't stat source directory: "
                    << from_path.value().c_str();
        return false;
    }
    // TODO(maruel): This is not necessary anymore.
    DCHECK(recursive || DirectoryExists(from_path));

    FilePath current = from_path;
    bool from_is_dir = DirectoryExists(from_path);
    bool success = true;
    FilePath from_path_base = from_path;
    if (recursive && DirectoryExists(to_path)) {
        // If the destination already exists and is a directory, then the
        // top level of source needs to be copied.
        from_path_base = from_path.DirName();
    }

    while (success && !current.empty()) {
        // current is the source path, including from_path, so append
        // the suffix after from_path to to_path to create the target_path.
        FilePath target_path(to_path);
        if (from_path_base != current) {
            if (!from_path_base.AppendRelativePath(current, &target_path)) {
                success = false;
                break;
            }
        }

        if (from_is_dir) {
            if (!DirectoryExists(target_path) && !::CreateDirectory(target_path.value().c_str(), NULL)) {
                DLOG(ERROR) << "CopyDirectory() couldn't create directory: "
                            << target_path.value().c_str();
                success = false;
            }
        } else if (!CopyFile(current, target_path)) {
            DLOG(ERROR) << "CopyDirectory() couldn't create file: "
                        << target_path.value().c_str();
            success = false;
        }

        current = traversal.Next();
        if (!current.empty())
            from_is_dir = traversal.GetInfo().IsDirectory();
    }

    return success;
}

bool PathExists(const FilePath& path)
{
    ThreadRestrictions::AssertIOAllowed();
    return (GetFileAttributes(path.value().c_str()) != INVALID_FILE_ATTRIBUTES);
}

bool PathIsWritable(const FilePath& path)
{
    ThreadRestrictions::AssertIOAllowed();
    HANDLE dir = CreateFile(path.value().c_str(), FILE_ADD_FILE, kFileShareAll,
        NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);

    if (dir == INVALID_HANDLE_VALUE)
        return false;

    CloseHandle(dir);
    return true;
}

bool DirectoryExists(const FilePath& path)
{
    ThreadRestrictions::AssertIOAllowed();
    DWORD fileattr = GetFileAttributes(path.value().c_str());
    if (fileattr != INVALID_FILE_ATTRIBUTES)
        return (fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0;
    return false;
}

bool GetTempDir(FilePath* path)
{
    wchar_t temp_path[MAX_PATH + 1];
    DWORD path_len = ::GetTempPath(MAX_PATH, temp_path);
    if (path_len >= MAX_PATH || path_len <= 0)
        return false;
    // TODO(evanm): the old behavior of this function was to always strip the
    // trailing slash.  We duplicate this here, but it shouldn't be necessary
    // when everyone is using the appropriate FilePath APIs.
    *path = FilePath(temp_path).StripTrailingSeparators();
    return true;
}

FilePath GetHomeDir()
{
    char16 result[MAX_PATH];
    if (SUCCEEDED(SHGetFolderPath(NULL, CSIDL_PROFILE, NULL, SHGFP_TYPE_CURRENT,
            result))
        && result[0]) {
        return FilePath(result);
    }

    // Fall back to the temporary directory on failure.
    FilePath temp;
    if (GetTempDir(&temp))
        return temp;

    // Last resort.
    return FilePath(L"C:\\");
}

bool CreateTemporaryFile(FilePath* path)
{
    ThreadRestrictions::AssertIOAllowed();

    FilePath temp_file;

    if (!GetTempDir(path))
        return false;

    if (CreateTemporaryFileInDir(*path, &temp_file)) {
        *path = temp_file;
        return true;
    }

    return false;
}

// On POSIX we have semantics to create and open a temporary file
// atomically.
// TODO(jrg): is there equivalent call to use on Windows instead of
// going 2-step?
FILE* CreateAndOpenTemporaryFileInDir(const FilePath& dir, FilePath* path)
{
    ThreadRestrictions::AssertIOAllowed();
    if (!CreateTemporaryFileInDir(dir, path)) {
        return NULL;
    }
    // Open file in binary mode, to avoid problems with fwrite. On Windows
    // it replaces \n's with \r\n's, which may surprise you.
    // Reference: http://msdn.microsoft.com/en-us/library/h9t88zwz(VS.71).aspx
    return OpenFile(*path, "wb+");
}

bool CreateTemporaryFileInDir(const FilePath& dir, FilePath* temp_file)
{
    ThreadRestrictions::AssertIOAllowed();

    wchar_t temp_name[MAX_PATH + 1];

    if (!GetTempFileName(dir.value().c_str(), L"", 0, temp_name)) {
        DPLOG(WARNING) << "Failed to get temporary file name in "
                       << UTF16ToUTF8(dir.value());
        return false;
    }

    wchar_t long_temp_name[MAX_PATH + 1];
    DWORD long_name_len = GetLongPathName(temp_name, long_temp_name, MAX_PATH);
    if (long_name_len > MAX_PATH || long_name_len == 0) {
        // GetLongPathName() failed, but we still have a temporary file.
        *temp_file = FilePath(temp_name);
        return true;
    }

    FilePath::StringType long_temp_name_str;
    long_temp_name_str.assign(long_temp_name, long_name_len);
    *temp_file = FilePath(long_temp_name_str);
    return true;
}

bool CreateTemporaryDirInDir(const FilePath& base_dir,
    const FilePath::StringType& prefix,
    FilePath* new_dir)
{
    ThreadRestrictions::AssertIOAllowed();

    FilePath path_to_create;

    for (int count = 0; count < 50; ++count) {
        // Try create a new temporary directory with random generated name. If
        // the one exists, keep trying another path name until we reach some limit.
        string16 new_dir_name;
        new_dir_name.assign(prefix);
        new_dir_name.append(IntToString16(GetCurrentProcId()));
        new_dir_name.push_back('_');
        new_dir_name.append(
            IntToString16(RandInt(0, std::numeric_limits<int16_t>::max())));

        path_to_create = base_dir.Append(new_dir_name);
        if (::CreateDirectory(path_to_create.value().c_str(), NULL)) {
            *new_dir = path_to_create;
            return true;
        }
    }

    return false;
}

bool CreateNewTempDirectory(const FilePath::StringType& prefix,
    FilePath* new_temp_path)
{
    ThreadRestrictions::AssertIOAllowed();

    FilePath system_temp_dir;
    if (!GetTempDir(&system_temp_dir))
        return false;

    return CreateTemporaryDirInDir(system_temp_dir, prefix, new_temp_path);
}

bool CreateDirectoryAndGetError(const FilePath& full_path,
    File::Error* error)
{
    ThreadRestrictions::AssertIOAllowed();

    // If the path exists, we've succeeded if it's a directory, failed otherwise.
    const wchar_t* full_path_str = full_path.value().c_str();
    DWORD fileattr = ::GetFileAttributes(full_path_str);
    if (fileattr != INVALID_FILE_ATTRIBUTES) {
        if ((fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0) {
            DVLOG(1) << "CreateDirectory(" << full_path_str << "), "
                     << "directory already exists.";
            return true;
        }
        DLOG(WARNING) << "CreateDirectory(" << full_path_str << "), "
                      << "conflicts with existing file.";
        if (error) {
            *error = File::FILE_ERROR_NOT_A_DIRECTORY;
        }
        return false;
    }

    // Invariant:  Path does not exist as file or directory.

    // Attempt to create the parent recursively.  This will immediately return
    // true if it already exists, otherwise will create all required parent
    // directories starting with the highest-level missing parent.
    FilePath parent_path(full_path.DirName());
    if (parent_path.value() == full_path.value()) {
        if (error) {
            *error = File::FILE_ERROR_NOT_FOUND;
        }
        return false;
    }
    if (!CreateDirectoryAndGetError(parent_path, error)) {
        DLOG(WARNING) << "Failed to create one of the parent directories.";
        if (error) {
            DCHECK(*error != File::FILE_OK);
        }
        return false;
    }

    if (!::CreateDirectory(full_path_str, NULL)) {
        DWORD error_code = ::GetLastError();
        if (error_code == ERROR_ALREADY_EXISTS && DirectoryExists(full_path)) {
            // This error code ERROR_ALREADY_EXISTS doesn't indicate whether we
            // were racing with someone creating the same directory, or a file
            // with the same path.  If DirectoryExists() returns true, we lost the
            // race to create the same directory.
            return true;
        } else {
            if (error)
                *error = File::OSErrorToFileError(error_code);
            DLOG(WARNING) << "Failed to create directory " << full_path_str
                          << ", last error is " << error_code << ".";
            return false;
        }
    } else {
        return true;
    }
}

bool NormalizeFilePath(const FilePath& path, FilePath* real_path)
{
    ThreadRestrictions::AssertIOAllowed();
    FilePath mapped_file;
    if (!NormalizeToNativeFilePath(path, &mapped_file))
        return false;
    // NormalizeToNativeFilePath() will return a path that starts with
    // "\Device\Harddisk...".  Helper DevicePathToDriveLetterPath()
    // will find a drive letter which maps to the path's device, so
    // that we return a path starting with a drive letter.
    return DevicePathToDriveLetterPath(mapped_file, real_path);
}

bool DevicePathToDriveLetterPath(const FilePath& nt_device_path,
    FilePath* out_drive_letter_path)
{
    ThreadRestrictions::AssertIOAllowed();

    // Get the mapping of drive letters to device paths.
    const int kDriveMappingSize = 1024;
    wchar_t drive_mapping[kDriveMappingSize] = { '\0' };
    if (!::GetLogicalDriveStrings(kDriveMappingSize - 1, drive_mapping)) {
        DLOG(ERROR) << "Failed to get drive mapping.";
        return false;
    }

    // The drive mapping is a sequence of null terminated strings.
    // The last string is empty.
    wchar_t* drive_map_ptr = drive_mapping;
    wchar_t device_path_as_string[MAX_PATH];
    wchar_t drive[] = L" :";

    // For each string in the drive mapping, get the junction that links
    // to it.  If that junction is a prefix of |device_path|, then we
    // know that |drive| is the real path prefix.
    while (*drive_map_ptr) {
        drive[0] = drive_map_ptr[0]; // Copy the drive letter.

        if (QueryDosDevice(drive, device_path_as_string, MAX_PATH)) {
            FilePath device_path(device_path_as_string);
            if (device_path == nt_device_path || device_path.IsParent(nt_device_path)) {
                *out_drive_letter_path = FilePath(drive + nt_device_path.value().substr(wcslen(device_path_as_string)));
                return true;
            }
        }
        // Move to the next drive letter string, which starts one
        // increment after the '\0' that terminates the current string.
        while (*drive_map_ptr++) { }
    }

    // No drive matched.  The path does not start with a device junction
    // that is mounted as a drive letter.  This means there is no drive
    // letter path to the volume that holds |device_path|, so fail.
    return false;
}

bool NormalizeToNativeFilePath(const FilePath& path, FilePath* nt_path)
{
    DebugBreak();
    return false;

//     ThreadRestrictions::AssertIOAllowed();
//     // In Vista, GetFinalPathNameByHandle() would give us the real path
//     // from a file handle.  If we ever deprecate XP, consider changing the
//     // code below to a call to GetFinalPathNameByHandle().  The method this
//     // function uses is explained in the following msdn article:
//     // http://msdn.microsoft.com/en-us/library/aa366789(VS.85).aspx
//     win::ScopedHandle file_handle(
//         ::CreateFile(path.value().c_str(),
//             GENERIC_READ,
//             kFileShareAll,
//             NULL,
//             OPEN_EXISTING,
//             FILE_ATTRIBUTE_NORMAL,
//             NULL));
//     if (!file_handle.IsValid())
//         return false;
// 
//     // Create a file mapping object.  Can't easily use MemoryMappedFile, because
//     // we only map the first byte, and need direct access to the handle. You can
//     // not map an empty file, this call fails in that case.
//     win::ScopedHandle file_map_handle(
//         ::CreateFileMapping(file_handle.Get(),
//             NULL,
//             PAGE_READONLY,
//             0,
//             1, // Just one byte.  No need to look at the data.
//             NULL));
//     if (!file_map_handle.IsValid())
//         return false;
// 
//     // Use a view of the file to get the path to the file.
//     void* file_view = MapViewOfFile(file_map_handle.Get(),
//         FILE_MAP_READ, 0, 0, 1);
//     if (!file_view)
//         return false;
// 
//     // The expansion of |path| into a full path may make it longer.
//     // GetMappedFileName() will fail if the result is longer than MAX_PATH.
//     // Pad a bit to be safe.  If kMaxPathLength is ever changed to be less
//     // than MAX_PATH, it would be nessisary to test that GetMappedFileName()
//     // not return kMaxPathLength.  This would mean that only part of the
//     // path fit in |mapped_file_path|.
//     const int kMaxPathLength = MAX_PATH + 10;
//     wchar_t mapped_file_path[kMaxPathLength];
//     bool success = false;
//     HANDLE cp = GetCurrentProcess();
//     if (::GetMappedFileNameW(cp, file_view, mapped_file_path, kMaxPathLength)) {
//         *nt_path = FilePath(mapped_file_path);
//         success = true;
//     }
//     ::UnmapViewOfFile(file_view);
//     return success;
}

bool IsOnNetworkDrive(const base::FilePath& path)
{
    win::ScopedHandle handle(
        ::CreateFileW(path.value().c_str(),
            GENERIC_READ,
            kFileShareAll,
            NULL,
            OPEN_EXISTING,
            FILE_FLAG_BACKUP_SEMANTICS, // Needed to open directory.
            NULL));

    if (!handle.IsValid())
        return false;

    // If able to get network information, then the file is on a network.
    FILE_REMOTE_PROTOCOL_INFO remote_proto_info = { 0 };
    return !!::GetFileInformationByHandleEx(handle.Get(), FileRemoteProtocolInfo,
        &remote_proto_info,
        sizeof(remote_proto_info));
}

// TODO(rkc): Work out if we want to handle NTFS junctions here or not, handle
// them if we do decide to.
bool IsLink(const FilePath& file_path)
{
    return false;
}

bool GetFileInfo(const FilePath& file_path, File::Info* results)
{
    ThreadRestrictions::AssertIOAllowed();

    WIN32_FILE_ATTRIBUTE_DATA attr;
    if (!GetFileAttributesEx(file_path.value().c_str(),
            GetFileExInfoStandard, &attr)) {
        return false;
    }

    ULARGE_INTEGER size;
    size.HighPart = attr.nFileSizeHigh;
    size.LowPart = attr.nFileSizeLow;
    results->size = size.QuadPart;

    results->is_directory = (attr.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
    results->last_modified = Time::FromFileTime(attr.ftLastWriteTime);
    results->last_accessed = Time::FromFileTime(attr.ftLastAccessTime);
    results->creation_time = Time::FromFileTime(attr.ftCreationTime);

    return true;
}

FILE* OpenFile(const FilePath& filename, const char* mode)
{
    ThreadRestrictions::AssertIOAllowed();
    string16 w_mode = ASCIIToUTF16(mode);
    return _wfsopen(filename.value().c_str(), w_mode.c_str(), _SH_DENYNO);
}

FILE* FileToFILE(File file, const char* mode)
{
    if (!file.IsValid())
        return NULL;
    int fd = _open_osfhandle(reinterpret_cast<intptr_t>(file.GetPlatformFile()), 0);
    if (fd < 0)
        return NULL;
    file.TakePlatformFile();
    FILE* stream = _fdopen(fd, mode);
    if (!stream)
        _close(fd);
    return stream;
}

int ReadFile(const FilePath& filename, char* data, int max_size)
{
    ThreadRestrictions::AssertIOAllowed();
    win::ScopedHandle file(CreateFile(filename.value().c_str(),
        GENERIC_READ,
        FILE_SHARE_READ | FILE_SHARE_WRITE,
        NULL,
        OPEN_EXISTING,
        FILE_FLAG_SEQUENTIAL_SCAN,
        NULL));
    if (!file.IsValid())
        return -1;

    DWORD read;
    if (::ReadFile(file.Get(), data, max_size, &read, NULL))
        return read;

    return -1;
}

int WriteFile(const FilePath& filename, const char* data, int size)
{
    ThreadRestrictions::AssertIOAllowed();
    win::ScopedHandle file(CreateFile(filename.value().c_str(),
        GENERIC_WRITE,
        0,
        NULL,
        CREATE_ALWAYS,
        0,
        NULL));
    if (!file.IsValid()) {
        DPLOG(WARNING) << "CreateFile failed for path "
                       << UTF16ToUTF8(filename.value());
        return -1;
    }

    DWORD written;
    BOOL result = ::WriteFile(file.Get(), data, size, &written, NULL);
    if (result && static_cast<int>(written) == size)
        return written;

    if (!result) {
        // WriteFile failed.
        DPLOG(WARNING) << "writing file " << UTF16ToUTF8(filename.value())
                       << " failed";
    } else {
        // Didn't write all the bytes.
        DLOG(WARNING) << "wrote" << written << " bytes to "
                      << UTF16ToUTF8(filename.value()) << " expected " << size;
    }
    return -1;
}

bool AppendToFile(const FilePath& filename, const char* data, int size)
{
    ThreadRestrictions::AssertIOAllowed();
    win::ScopedHandle file(CreateFile(filename.value().c_str(),
        FILE_APPEND_DATA,
        0,
        NULL,
        OPEN_EXISTING,
        0,
        NULL));
    if (!file.IsValid()) {
        VPLOG(1) << "CreateFile failed for path " << UTF16ToUTF8(filename.value());
        return false;
    }

    DWORD written;
    BOOL result = ::WriteFile(file.Get(), data, size, &written, NULL);
    if (result && static_cast<int>(written) == size)
        return true;

    if (!result) {
        // WriteFile failed.
        VPLOG(1) << "Writing file " << UTF16ToUTF8(filename.value()) << " failed";
    } else {
        // Didn't write all the bytes.
        VPLOG(1) << "Only wrote " << written << " out of " << size << " byte(s) to "
                 << UTF16ToUTF8(filename.value());
    }
    return false;
}

// Gets the current working directory for the process.
bool GetCurrentDirectory(FilePath* dir)
{
    ThreadRestrictions::AssertIOAllowed();

    wchar_t system_buffer[MAX_PATH];
    system_buffer[0] = 0;
    DWORD len = ::GetCurrentDirectory(MAX_PATH, system_buffer);
    if (len == 0 || len > MAX_PATH)
        return false;
    // TODO(evanm): the old behavior of this function was to always strip the
    // trailing slash.  We duplicate this here, but it shouldn't be necessary
    // when everyone is using the appropriate FilePath APIs.
    std::wstring dir_str(system_buffer);
    *dir = FilePath(dir_str).StripTrailingSeparators();
    return true;
}

// Sets the current working directory for the process.
bool SetCurrentDirectory(const FilePath& directory)
{
    ThreadRestrictions::AssertIOAllowed();
    BOOL ret = ::SetCurrentDirectory(directory.value().c_str());
    return ret != 0;
}

int GetMaximumPathComponentLength(const FilePath& path)
{
    ThreadRestrictions::AssertIOAllowed();

    wchar_t volume_path[MAX_PATH];
    if (!GetVolumePathNameW(path.NormalizePathSeparators().value().c_str(),
            volume_path,
            arraysize(volume_path))) {
        return -1;
    }

    DWORD max_length = 0;
    if (!GetVolumeInformationW(volume_path, NULL, 0, NULL, &max_length, NULL,
            NULL, 0)) {
        return -1;
    }

    // Length of |path| with path separator appended.
    size_t prefix = path.StripTrailingSeparators().value().size() + 1;
    // The whole path string must be shorter than MAX_PATH. That is, it must be
    // prefix + component_length < MAX_PATH (or equivalently, <= MAX_PATH - 1).
    int whole_path_limit = std::max(0, MAX_PATH - 1 - static_cast<int>(prefix));
    return std::min(whole_path_limit, static_cast<int>(max_length));
}

bool CopyFile(const FilePath& from_path, const FilePath& to_path)
{
    ThreadRestrictions::AssertIOAllowed();
    if (from_path.ReferencesParent() || to_path.ReferencesParent())
        return false;

    // NOTE: I suspect we could support longer paths, but that would involve
    // analyzing all our usage of files.
    if (from_path.value().length() >= MAX_PATH || to_path.value().length() >= MAX_PATH) {
        return false;
    }

    // Unlike the posix implementation that copies the file manually and discards
    // the ACL bits, CopyFile() copies the complete SECURITY_DESCRIPTOR and access
    // bits, which is usually not what we want. We can't do much about the
    // SECURITY_DESCRIPTOR but at least remove the read only bit.
    const wchar_t* dest = to_path.value().c_str();
    if (!::CopyFile(from_path.value().c_str(), dest, false)) {
        // Copy failed.
        return false;
    }
    DWORD attrs = GetFileAttributes(dest);
    if (attrs == INVALID_FILE_ATTRIBUTES) {
        return false;
    }
    if (attrs & FILE_ATTRIBUTE_READONLY) {
        SetFileAttributes(dest, attrs & ~FILE_ATTRIBUTE_READONLY);
    }
    return true;
}

bool SetNonBlocking(int fd)
{
    unsigned long nonblocking = 1;
    if (ioctlsocket(fd, FIONBIO, &nonblocking) == 0)
        return true;
    return false;
}

// -----------------------------------------------------------------------------

namespace internal {

    bool MoveUnsafe(const FilePath& from_path, const FilePath& to_path)
    {
        ThreadRestrictions::AssertIOAllowed();

        // NOTE: I suspect we could support longer paths, but that would involve
        // analyzing all our usage of files.
        if (from_path.value().length() >= MAX_PATH || to_path.value().length() >= MAX_PATH) {
            return false;
        }
        if (MoveFileEx(from_path.value().c_str(), to_path.value().c_str(),
                MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING)
            != 0)
            return true;

        // Keep the last error value from MoveFileEx around in case the below
        // fails.
        bool ret = false;
        DWORD last_error = ::GetLastError();

        if (DirectoryExists(from_path)) {
            // MoveFileEx fails if moving directory across volumes. We will simulate
            // the move by using Copy and Delete. Ideally we could check whether
            // from_path and to_path are indeed in different volumes.
            ret = internal::CopyAndDeleteDirectory(from_path, to_path);
        }

        if (!ret) {
            // Leave a clue about what went wrong so that it can be (at least) picked
            // up by a PLOG entry.
            ::SetLastError(last_error);
        }

        return ret;
    }

    bool CopyAndDeleteDirectory(const FilePath& from_path,
        const FilePath& to_path)
    {
        ThreadRestrictions::AssertIOAllowed();
        if (CopyDirectory(from_path, to_path, true)) {
            if (DeleteFile(from_path, true))
                return true;

            // Like Move, this function is not transactional, so we just
            // leave the copied bits behind if deleting from_path fails.
            // If to_path exists previously then we have already overwritten
            // it by now, we don't get better off by deleting the new bits.
        }
        return false;
    }

} // namespace internal
} // namespace base
